<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>网页计算器</title>
</head>
<body>
    <p>整数1：<input id="num1" type="text"></p>
    <p>整数2：<input id="num2" type="text"></p>
    <p>
        <input type="button" value="相加" onclick="calc(add)">
        <input type="button" value="相减" onclick="calc(sub)">
        <input type="button" value="相乘" onclick="calc(mul)">
        <input type="button" value="相除" onclick="calc(div)">
    </p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
    <p>结果：<input id="result" type="text" readonly></p>
    <script>
        function calc(func) {
            var result = document.getElementById('result');
            var num1 = parseInt(document.getElementById('num1').value);
            var num2 = parseInt(document.getElementById('num2').value);
            if (isNaN(num1)||isNaN(num2)){
                alert('请输入数字');
                return false;
            }
            result.value = func(num1,num2);
        }
        function add(num1,num2){
            return num1+num2;
        }
        function sub(num1,num2){
            return num1-num2;
        }
        function mul(num1,num2){
            return num1*num2;
        }
        function div(num1,num2){
            if(num2==0){
                alert('除数不能为0');
                return '';
            }
            return num1/num2;
        }
        </script>
        <h1><a href="../default.html">返回主页</a></h1>
</body>
</html>